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Homework Help: Motion of a charge

  1. Feb 27, 2010 #1
    Helium ion , He (2+) travelling at 1.0 x 10^5 m/s pass through a region where there is a uniform electric field of 2 x 10^4 V/m perpendicular to their initial path and extending for 0.10 m . Through what angle are they deflected ? [Charge of the electron , e=-1.6 x 10^(-19)C , mass of helium ion , m=6.7 x 10^(-27)kg]

    well , this is what i did :

    Resolve the velocity into 2 components , Vx and Vy where

    Vx=1.0 x 10^5



    After doing some substitution , i found a to be 9.56 x 10^11


    Vy^2=2(9.56 x 10^11 )(0.10)

    Vy=4.4 x 10^5

    so the angle = tan^(-1) Vy/Vx

    = 77 degree

    but the given is about 84 degree ..
  2. jcsd
  3. Feb 27, 2010 #2


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    Homework Helper

    Hi thereddevils, welcome to PF.
    The electric field is extended 0.10 m horizontally, not vertically.
    Find time t required to cross this region by the helium ion.
    In this time interval find Vy.
  4. Feb 27, 2010 #3
    thank you , bhat !
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